JEE Main 2023 · 11 April · morning · Single correct · +4 / −1
The set which does not have ambidentate ligand(s) is :
- (a) C₂ O₄ ²⁻, NO₂ ⁻, NCS⁻
- (b) C₂ O₄ ²⁻, ethylene diammine, H₂ O
- (c) NO₂⁻, C₂ O₄ ²⁻, EDTA ⁴⁻
- (d) EDTA⁴⁻, NCS⁻, C₂ O₄ ²⁻
Answer and solution
Answer (b) C₂ O₄ ²⁻, ethylene diammine, H₂ O
Solution
Chemistry ma’am · 3 steps
Ambidentate means one donor atom at a time, chosen from two possible atoms. Look for NO2 and NCS.
- What ambidentate means. An ambidentate ligand has two different atoms that can donate, but it binds through only one of them at a time. NO₂⁻ binds through N (nitro) or O (nitrito), and NCS⁻ binds through N (isothiocyanato) or S (thiocyanato).
- Do not confuse. Oxalate, ethylenediamine and EDTA⁴⁻ bind through two or more atoms at the same time, so they are bidentate or polydentate. They are not ambidentate.
Option Ligands Ambidentate one present? (a) C₂O₄²⁻, NO₂⁻, NCS⁻ Yes: NO₂⁻ and NCS⁻ (b) C₂O₄²⁻, en, H₂O None: bidentate, bidentate, monodentate (c) NO₂⁻, C₂O₄²⁻, EDTA⁴⁻ Yes: NO₂⁻ (d) EDTA⁴⁻, NCS⁻, C₂O₄²⁻ Yes: NCS⁻ - So. Only set (b) has no ambidentate ligand. H₂O donates only through O, and en and oxalate are chelating ligands. The answer is (b).
The idea to keep. Ambidentate means a choice between two donor atoms, one at a time. Chelating means several donor atoms together. The usual ambidentate ligands are NO₂⁻, SCN⁻ and CN⁻.
Answer from the NTA final answer key. Solution by PrepWiser.